How can I control the speed of a fluid simulation?
Well, there is no way to do exactly what you want, but these are the basics.

First of all, ignore the comments about start values and such for the domain. The only thing that matters is inflow velocity. To begin the inflow at frame 100, go to frame 99, and in the inflow settings uncheck "enabled" and key frame it. Then go to frame 100 and check "enabled" and key frame it. Now the inflow will start at frame 100.

Then you have to play around with the settings for inflow velocity until you get what you want.

As for the basic domain settings, if you want 10 seconds of animation, the start value should be 0 and the end value should be 10. Speed should be 1.